The present invention relates to devices for tensioning engine belts and more particularly to a length adjustable belt tensioning arm for tensioning engine belts.
It is often necessary to tension belts in an engine either when installing a new belt or tightening an older stretched out belt. Prior art arms for tensioning engine belts are well known. An example of a prior art belt tensioning arm 2 is shown in FIG. 1. The belt tensioning arm 2 is fixed in length, has a slot 4 formed therein and a pair of holes in which bolts 6 are inserted for fixedly securing the arm 2 to the engine. A bolt 8 is used to secure the tensioning arm 2 to an engine component having a belt, such as an alternator or the like. To tension the alternator belt, the bolt 8 is loosened. A pry bar, or other extended lever, is placed against the alternator and used to move the alternator and the bolt 8 forward, relative to the tensioning arm 2, thereby tensioning the belt. The bolt 8 is then tightened as the alternator is held in position by the pry bar, thereby securing the alternator in place.
This method of tensioning the alternator belt is effective, but it also presents many unneeded difficulties. For example, an extraneous pry bar is necessary. Using the pry bar can be awkward. The pry bar can also damage engine components. Furthermore it is difficult for the operator to tighten bolt 8 while maintaining tension on the alternator and the belt will loosen if bolt 8 becomes loose.
Other devices for tensioning engine belts are known. However, many of these devices require tearing down a significant portion of the engine to install them, are complicated in operation and are not retrofittable to existing engines without modification to the engine.
A need exists for a tensioning arm that overcomes the aforementioned disadvantages of the prior art and is easily retrofitted in an engine.
In accordance with one aspect of the present invention there is provided a tensioning device including an adjustable tensioning arm having first and second opposed ends, a first mounting bracket secured to the first end of the adjustable tensioning arm, and a second mounting bracket pivotally connected to the second end of the adjustable tensioning arm. The adjustable tensioning arm includes a middle member having first and second opposed ends, a first end member engaged with and extending from the first end of the middle member and a second end member engaged with and extending from the second end of the middle member.
In a preferred embodiment, the middle member is an internally threaded tube, the first end member is a first externally threaded rod and the second end member is a second externally threaded rod.
In accordance with another aspect of the present invention there is provided a tensioning device including an adjustable tensioning arm having first and second opposed ends, a first mounting bracket secured to the first end of the adjustable tensioning arm, and a second mounting bracket pivotally connected to the second end of the adjustable tensioning arm. The adjustable tensioning arm includes an elongated threaded rod, and an elongated clevis having a threaded hole formed therein that receives the threaded rod.
In accordance with another aspect of the present invention there is provided a method of adjustably tensioning a belt using a device having an adjustable tensioning arm and first and second mounting brackets connected to the ends thereof. The first mounting bracket is affixed to component A and the second mounting bracket is affixed to component B. The belt is coupled to component A. The method includes the steps of lengthening the adjustable tensioning arm and tightening a pair of elements for preventing rotation of a middle member. The lengthening of the adjustable tensioning arm includes the steps of loosening the pair of elements for preventing rotation of a middle member and rotating a middle member having first and second opposed ends, such that a pair of end members engaged with the first and second opposed ends of the middle member respectively extend further therefrom. The lengthening of the adjustable tensioning arm causes component A to move, thereby tensioning the belt.